High pressure will continue to build down from the northwest
overnight. Low pressure will develop off the Mid- Atlantic
coast on Tuesday. The low will track to a position off southern
New England on Wednesday then south of Nova Scotia on Thursday.

-- End Changed Discussion --

&&
.NEAR TERM /THROUGH TUESDAY/...

-- Changed Discussion --

647 PM Update...
Radar loop showed some light returns dropping s from Canada in
the form of light snow/flurries. The latest NAM12 showed llvl
convergence weakening over the next 3 hrs. This should allow for
light snow to die off. NAM12 soundings showed llvls drying out
in the next 3 hrs. Satl imagery is confirming this w/clouds starting
to scatter out. This trend looks like it will continue into the
overnight period and therefore, adjustments were made to the
sky conditions to reflect this thinking.
Hrly temps were adjusted the fit the current trends showing
temps to stay up from the previous thinking due the gusty winds
and clouds, especially across northern and eastern areas.
Previous Discussion...
High pressure continues to build down from central Canada as
low pressure both surface and aloft remains well to our
northeast. Some moisture wrapping south from the low will bring
patchy stratocumulus clouds across the north tonight and some
flurries may be around this evening. Otherwise, tonight will be
dry and cold and continued breezy. A corridor of dry air will
run southeast from the high across Downeast areas on Tuesday
while some moisture continues to back south from Canada across
the north. This will bring variable cloudiness over the north
while Downeast is mostly sunny on Tuesday. Afternoon highs will
be a bit higher than Monday`s highs but still around 5 degrees
below normal for the first day of spring.

-- End Changed Discussion --

&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
On Tuesday night, the surface high centered over James Bay will
remain in control with a ridge line extending into Maine. The
deep low level cold air will remain entrenched and the primary
question will be whether a subsidence inversion will hold
stratocumulus or if radiational cooling will produce lows below
guidance. For now, will go just below under guidance rather than
betting big as northwesterly flow reduces confidence in clear
skies and calm winds all night. The high remains in control
Wednesday with a strengthening NE flow resulting from a
tightening pressure gradient between the James Bay high and a
deepening surface low off the Delmarva peninsula. This means
both increasing stratocumulus advecting from the east and high
clouds thickening later in the day as moisture above H500
increases. Have leaned towards GFS H850 moisture fields for
Wednesday`s cloud forecast. Things become more interesting
Wednesday night. The vertically stacked low off the Delmarva
coast will send an its wraparound occlusion towards the
coast...accompanied by a shortwave rotating around the closed
upper low. At the same time, the entire closed upper low will
drift northward towards eastern Maine or Nova Scotia Wednesday
night into Thursday as northern and southern streams phase. This
time, there`s no blocking upper high to prevent the upper low
from drifting northward. While the occlusion will be weakening
and the surface low will be well offshore, moisture wrapped
around the upper low in the trowal could affect the forecast
area for much of Thursday. This will be an all-snow event, with
the possible exception of some sleet towards Eastport due to
warm air aloft in the occlusion. Ultimately, snowfall amounts
and duration will be based on the exact track of the upper low,
but certainly the current trend is pushing the upper low closer
to Maine. Since we`re dealing with closed upper lows, prefer
using ensemble means rather any particular deterministic model.
Also of note is a strong northeasterly H900 jet coinciding with
occlusion and potential for some elevated instability. This
could generate some heavier snowfall towards the coast on
Wednesday night if it materializes. The Down East region stands
the best chance of advisory or warning level snowfalls from this
system and the Allagash would likely receive the least as
amounts taper to the NW. The LLJ will help create surface wind
gusts over 30 mph...and possibly up to 40 mph Wednesday night
into Thursday. Thus blowing snow will be a threat. Have not
entered that into the forecast yet, but it should go into the
forecast as confidence grows in this event. Furthermore, the
winds could generate a storm surge along the coast that could
cause some minor coastal flooding.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Thursday night into Friday, guidance is in decent agreement with
regard to the upper low pulling away into the Canadian
Maritimes, weak ridging over the area and a north to northwest
flow. This probably means a lot of cu and stratocu and a few
flurries. Things become more confused Saturday into Sunday as an
omega block is established over eastern/central Canada. Maine
will be on the right side of the block and the confusion lies in
exactly where the closed low will set up. GFS has the upper low
over the area with a chance of snow showers though the weekend.
Previous runs of the ECMWF and GEMS put the closed low further
north and located Maine nearer to a shortwave rotating on the
south side of the closed low. However, with today`s 12Z
guidance, the ECMWF and GEMS have fallen in line with the GFS.
The high pressure part of the omega increases influence on the
area Monday into Tuesday next week. This promises to bring some
much warmer temperatures with highs returning to the 40s.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: VFR conditions are expected across the area today and
tonight.
SHORT TERM: All sites will be VFR Tuesday night and Wednesday. IFR
conditions...tempo LIFR...will hit the coast on Wednesday
evening and spread north overnight and continue Thursday. The
snow will be accompanied by strong NE winds gusting over 30 mph
and possible LLWS with up to 50kt of wind near 3000 ft. Conditions
will lift to MVFR later Thursday into Thursday night. In
general, expect mostly MVFR cigs north of HUL later Thursday
into Sunday while VFR conditions are expected towards BGR and
BHB.
&&
.MARINE...
NEAR TERM: A SCA will continue into mid morning Tuesday. Winds
should then finally drop below SCA from late morning into
Tuesday afternoon as high pressure crests over the waters.
SHORT TERM: A Gale Warning seems like a strong bet for Wednesday
afternoon into Thursday morning...tapering to an SCA Thursday
morning into Thursday night.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...